MAP40: Refueling Base (PlayStation Doom)

MAP40: Refueling Base is the fortieth level of the Sony PlayStation and Sega Saturn versions of Doom, and the tenth level of the Doom II episode. It is based on the original MAP10: Refueling Base, with modifications made to adapt the map to the consoles' limitations. The authors of the original map are Tom Hall and Sandy Petersen.

Essentials
Head down the stairs in front and you and go through the doorway just on the right. Go through this room and head through the doorway at the opposite end to a long outdoor hallway. Turn left and go through the door ahead to a room containing many silver alcoves, zombiemen and shotgun guys. Carefully make your way through the room and retrieve the yellow keycard from an alcove in the south-east corner. Once acquired, backtrack to the outdoor hallway.

Make your way to the opposite end of the long outdoor area and open the door there. The next room is very large and dark, and contains a number of imps and arachnotrons. Go through either of the tunnels at the north end of this room and you will reach a stairway leading into a brightly lit alcove in the wall. Climb the stairs and the wall in front of you will open, revealing the blue keycard. Pick it up and return outside once more. If the wall containing the blue key closes, you can press use on the wall to open it manually.

Return to the outdoor hallway. About halfway down is a small passage leading to a round room with fuel tanks. Go through the door to the south to enter a dark room with numerous enemies. Head through the yellow door in the south-east corner, then through a small room to a blue door. Go through here and follow the passage round the metal grates to the exit door; watch out for arachnotrons in the room above who may teleport in to block your path. Once you are through the exit door, press the switch behind it to finish the level.

Other points of interest
At the start of the level, you will see a wall on your right with blue triangles. Open this wall to find an alcove containing a shotgun.

From the level start, head down the stairs and through the doorway just on your right. In front of you is a column with cracked gray stone walls - press use on it and it will lower to reveal a chaingun, plus four stimpacks on Hurt Me Plenty or Ultra Violence.

The dark room on the east side of the level has a single brightly-lit square indicated by a blue ceiling light. Stepping on this square opens two alcoves to the north, which contain four demons but also hold a box of rockets, a box of bullets and a BFG9000.

From the stone room in the south-east corner of the level, you can enter a small chamber to the south which holds a soulsphere and a plasma gun. To get the items, you need to enter the north alcove in this chamber to lower one lift, then quickly press the switch in the south alcove to lower a second lift.

The south-west room overlooking the exit door contains four arachnotrons, but also contains an invulnerability sphere and one or two energy cell packs. The room can be entered from secret #7, or from the dark southern room once you have the blue key. Doing so lets you kill the arachnotrons early, instead of having them teleport into the rooms before the exit where they would block your path.

Secrets

 * 1) The north-east room has many silver alcoves in its walls. Most alcoves have back walls which match their side textures, but some of the alcoves have a distinctive fading texture on their backs. The first of these alcoves is located on the north wall, near the north-east corner of the room. Shoot the wall with a hitscan weapon to open an alcove behind it with a soulsphere. (sector 6)
 * 2) Like secret #1, but located in the alcove on the east side of the western-most column in the center of the room. Shoot the back wall here to open an alcove with a megaarmor and a light amplification visor. (sector 41)
 * 3) Like secrets #1 and #2, located in the alcove on the west side of the south-east column in the center of the room. Shoot the back wall here to open an alcove with an energy cell pack. (sector 8)
 * 4) Across from and a short distance south of secret #3 is another alcove with a distinctive back wall. This alcove contains a berserk pack and other pickups. (sector 37) This secret also contains two lost souls on Hurt Me Plenty skill level, joined by six spectres on Ultra Violence.
 * 5) Directly opposite the alcove that contained the yellow keycard is yet another alcove with a shootable back wall. Behind it is a passage containing a number of demons, with a backpack at the end. (sector 16)
 * 6) At the end of secret #5 is a concrete wall; open this wall and step through it to be teleported to a passage connected to the arachnotron chamber overlooking the exit. (sector 181) This passage also contains a box of bullets and an invulnerability powerup, letting you kill the arachnotrons from relative safety.
 * 7) Near the center of the level is a circular room with four gray "fuel tanks" on its upper floor. Enter this room through the passage on the east side to open the west fuel tank. (sector 126) This tank contains two boxes of bullets, among other pickups.
 * 8) Like secret #7, but enter from the western passage to open the east fuel tank. (sector 117) This tank also contains two boxes of bullets and other items.
 * 9) Like secrets #7 and #8, but enter from the south passage to open both center fuel tanks. (sector 124) The south tank contains a radiation shielding suit.
 * 10) See secret #9, the center tank contains two stimpacks and four health bonuses. (sector 128)
 * 11) From the "fuel tank" room, go through the western exit and follow the fork in the path to the right. You will be taken to a room with a pair of sludge pools. On the west wall near the entrance to this room is a brightly-lit triangle - step into this triangle to open a secret passage in the nukage pool on the left. At the end of the passage is a series of steps leading up to a megasphere. (sector 132)
 * 12) There is a large dark room in the eastern side of the level which has a single blue light on the ceiling. In the south-east corner of this room is a misaligned wall with a small metal step at its base - open this wall to reveal a secret passage leading to another room. (sector 83) The passage also contains a light amplification visor.
 * 13) After passing through the shortcut in secret #12 and arriving in the next room, follow the wall on your right until you come to a pair of short green columns. Open the wall between these columns to reveal an alcove with a berserk pack and many armor bonuses. (sector 80)
 * 14) From secret #13, continue west in this room until you reach a brown metal door in the northwest corner. Go through the door and pick up the rocket launcher to the right. From the platform the rocket launcher was on, run onto the platform straight ahead holding the armor. (sector 115)
 * 15) In the same room as secret #14, press the wall of the south platform to lower it like a lift. (sector 136) The platform holds two boxes of rockets.

Comparison of versions
Numerous changes were made to this level compared to the PC version.

Room design

 * All switches use a skull switch on metal wall texture.
 * All nukage pools are changed to sludge.
 * The "entrance door" in the starting room is removed, with a pool of blood and guts left in its place.
 * The large square pillar east of the start point, which lowers to reveal spectres when interacted with, uses a cracked stone texture instead of vines.
 * The central "fuel tanks" near the center of the level count as one secret instead of two.
 * The brightly-lit square in the large eastern room, which opens two chambers containing demons when stepped on, is larger.
 * The steps leading up to secret #11 use rapidly-flashing lights and are not flagged as secret.
 * The energy cells in the south-west room are replaced with an energy cell pack, or two on Hurt Me Plenty and Ultra Violence.
 * The transparent grate next to the exit door is replaced with two windows that have metal fences.
 * The gray grates in the windows of the south-western room are replaced with metal fences.

Monster placement

 * The cyberdemon in the south-western corner of the map (or baron of Hell on the I am a Wimp and Not Too Rough skill levels) is replaced with four arachnotrons on all skill levels.
 * Pain elementals are replaced with cacodemons.
 * Two of the chaingunners in secret #4 are replaced with lost souls, and the other two are removed without replacement.
 * Two spectres hiding in the gray column east of the start point do not appear on Hurt Me Plenty.

Music
The map uses the following music tracks:

Player spawns
This level contains nine spawn points:
 * 1) facing south-east. (thing 409)
 * 2) facing east. (thing 410)
 * 3) facing north. (thing 411)
 * 4) facing south-west. (thing 412)
 * 5) facing west. (thing 413)
 * 6) facing north. (thing 414)
 * 7) facing north. (thing 415)
 * 8) facing west. (thing 416)
 * 9) facing east. (thing 417)

Things
This level contains the following numbers of things per skill level: